1. Field of the Invention
The present invention relates to a weather strip including a molded portion and an extruded portion, wherein the molded portion is integrally formed on the end of the extruded portion.
2. Description of Related Art
FIGS. 5 to 8 show a conventional opening trim 50 of a weather strip. The opening trim 50 is formed by connecting integrally an end portion of a first extruded portion 51a to an end portion of a molded portion 61 and connecting the opposite end portion of the molded portion 61 to a second extruded portion 51b linearly. The symbol xe2x80x9cSxe2x80x9d designates a borderline, or an outline of the connecting end portions between the extruded portions 51a and 51b and the molded portion 61. Extruded portions 51a and 51b are substantially same components and will be referred to generically as extruded portion 51.
The extruded portion 51 shown in FIG. 7 and the molded portion 61 shown in FIG. 8 comprise attachment portions 52 and 62, respectively, having a generally U-shaped cross section. Attachment portions 52 and 62 attach to a flange 2 at the periphery of a door opening of an automobile body 1, as shown in FIG. 9. Further, the extruded portion 51 and the molded portion 61 comprises a hollow sealing portion 53 and 63, respectively, which are deformable elastically under the pressing of a door 3 when the door 3 is closed. Further, either extruded portion 51a or 51b may include a covering lip portion 54 protruding from the attachment portion 52 and covering the edge of an inner garnish (not shown). The conventional opening trim 50 shown in FIGS. 5 to 8 is also illustrated within dotted circle A depicted in FIG. 9.
The extruded portion 51 in FIG. 7 is integrally formed by co-extrusion molding the attachment portion 52, the hollow sealing portion 53 and the covering lip portion 54. A solid ethylene-propylene-diene copolymer (EPDM) rubber forms the attachment portion 52 and the covering lip portion 54, and a sponge EPDM rubber forms the hollow sealing portion 53. A metal insert 55, which may be made of separable pieces, is embedded in the attachment portion 52. A decorative cover 56, extending from the attachment portion 52 to the covering lip portion 54, is formed on the outer surface of the extruded portions 51a and 51b by thermal fusion bonding of a resin film, a thermoplastic elastomer film or a piece of fabric (cloth) after the completion of the extrusion molding process.
The attachment portion 62 and the hollow sealing portion 63 are molded from a solid EPDM rubber to integrally form the molded portion 61 shown in FIG. 8. More specifically, the end portions of the two extruded portions 51a and 51b are held in a metal mold (not shown), whereby the end portions of the extruded portions 51a and 51b are set facing a cavity of the metal mold. Then, a solid EPDM rubber material is injected into the cavity and vulcanized to thereby form the molded portion 61. Simultaneously with this injection molding process, the extruded portions 51a and 51b are integrally connected to the resulting molded portion 61.
However, when the molded portion 61 is formed from a solid EPDM rubber material, the metal mold temperature required for the vulcanization of the rubber is as high as 180 to 200xc2x0 C. Such a high metal mold temperature causes the decorative cover 56 to melt. Thus, to prevent such melting or to concealing the melting defects, the following countermeasures are employed.
(1) When the decorative cover 56 extends to the end of the extruded portion 51, the decorative cover 56 is also held within the metal mold. When the injection molding process occurs, the decorative cover 56 is also melted which causes melting flaws or holding flaws to form at the segment where the ends of the extruded portion 51 are held. Then, as shown in FIG. 5 by a double-dotted chain line, a decorative cover portion 56x at the end portion of the extruded portion 51, a part of the attachment portion 52, and the covering lip portion 54 were removed together by a stepwise cutting process. However, the stepwise cutting was an extremely troublesome process.
(2) Further, without such stepwise cutting, the decorative cover 56 is melted to form the molten flaws or holding flaws as described above. Thus, it was necessary to remove and conceal the flaws by buffing. The buffing process required extra process steps. In addition, there were other manufacturing problems, for example, in cases where a decorative cover 56 was applied with an embossed pattern, the embossed pattern was erased. Another example is in the case of a decorative cover 56 made of a fabric, the buffing process could not be applied. Furthermore, when the molded portion 61 is formed of a solid EPDM rubber, both the attachment portion 62 and a sealing portion 63 have a black color appearance due to carbon black being used as a reinforcing material for the rubber.
Then, in the case where the extruded portions 51a and 51b, positioned on both sides of the molded portion 61, include the decorative cover 56, respectively, the outer color differs from the molded portion 61 causing a deterioration in the appearance of the weather strip. Further, in a case where the molded portion 61 is formed of a solid EPDM rubber, the attachment portion 62 and the sealing portion 63 are formed of an identical material. So, if the design emphasis is placed on the softness of the rubber for sealing of the sealing portion 63, the rubber material may be made too soft. As a result, the gripping force of the attachment portion 62 to the flange is weakened. On the other hand, if the design emphasis is placed on the gripping force of the flange and the rubber material may be made too hard, the sealing quality and door closing capability of the weather strip deteriorated. Accordingly, it was difficult to design a weather strip while establishing a balance between the sealing quality and the gripping force to the flange.
It is an object of the invention to form a molded portion at a low temperature, that does not contain molten flaws or holding flaws on an extruded portion by forming a sealing portion of the molded portion from a soft or sponge thermoplastic elastomer (hereinafter referred to as TPE), and forming an attachment portion of the molded portion from a semi-rigid resin. This configuration is designed to obtain a load necessary for the elastic deformation of the sealing portion of the molded portion by forming the sealing portion with a soft or sponge TPE material, and to obtain the required gripping force of the molded portion by forming the attachment portion with the semi-rigid resin material.
It is another object of the invention to unify the tone and improve the appearance of the entire weather strip connected in series by making the color of the semi-rigid resin of the attachment portion of the molded portion identical to the color of a decorative cover of the extruded portion.
A first invention resides in a weather strip comprising an extruded portion and a molded portion which is integrally connected to an end portion of the extruded portion. The extruded portion comprises a sealing portion formed by extrusion molding a sponge rubber, soft TPE or sponge TPE and an attachment portion having a separable core member embedded therein and formed by co-extrusion molding from a solid rubber, low foamed rubber or TPE. The molded portion comprises a sealing portion formed of a soft TPE or sponge TPE and an attachment portion formed of a semi-rigid resin. The semi-rigid resin employed within the present invention has a hardness such that it does not lose its own shape after the molding process, and the concept of this semi-rigid resin also encompasses a thermoplastic elastomer.
A second invention resides in a process for manufacturing a weather strip comprising an extruded portion and a molded portion wherein the molded portion is integrally connected to an end portion of the extruded portion. The process comprises the steps of setting the end portion of the extruded portion in a mold cavity. The extruded portion includes a sealing portion, formed by extrusion molding a sponge rubber, soft TPE or sponge TPE, and an attachment portion, having a separable core member embedded and formed by co-extrusion molding from a solid rubber, low foamed rubber or TPE. Then, a semi-rigid resin material is injected into the mold cavity to form an attachment portion of the molded portion to integrally connect the attachment portion of the molded portion to the attachment portion of the extruded portion. Next, a soft or sponge TPE material is injected into the mold cavity to form a sealing portion of the molded portion to integrally connect the sealing portion of the molded portion to the sealing portion of the extruded portion.
In either the first or second invention, the extruded portion may comprise a covering lip portion, which is formed integrally to the attachment portion of the extruded portion and protruding therefrom. When the extruded portion further comprises a decorative cover formed of a resin, TPE or foamed material thereof and when the decorative cover is formed on the outer surface of the attachment portion or the covering lip portion of the extruded portion, the decorative cover can extend as far as the terminal edge of the end of the extruded portion without requiring stepwise cutting. In such a case, it is preferable that the metal mold temperature is set to a temperature that does not melt the decorative cover. The metal mold temperature is preferably 60xc2x0 C. to 80xc2x0 C.
In the first invention, the TPE for the sealing portion of the molded portion preferably has a Shore A type hardness of 30xc2x0 to 60xc2x0. In contrast, the semi-rigid resin for the attachment portion of the molded portion preferably has a Shore D type hardness of 30xc2x0 to 65xc2x0. The decorative cover and the attachment portion of the molded portion preferably have an identical color. No core member is embedded in the attachment portion of the molded portion.
In either the first or second invention, the molded portion may be formed in a linear shape or a curved shape.
A solid rubber, low foamed rubber or TPE may be used as a molding material for the attachment portion of the extruded portion as in the conventional case. An EPDM solid rubber or EPDM low foamed rubber having a foaming ratio of 10% to 25% is preferable to use the material for the attachment portion of the extruded portion. A sponge rubber or soft or sponge TPE is applicable as a molding material for the sealing portion of the extruded portion as in the conventional case. xe2x80x9cRubberxe2x80x9d embraces an EPDM rubber, while xe2x80x9csoft or sponge TPExe2x80x9d embraces an olefin-based TPE (TPO) and styrene-based TPE (SBC). Especially, a TPO is preferably used. The sealing portion is a hollow or a lip. Especially, a hollow sealing portion is preferably used.
A soft or sponge TPE is applicable as a molding material for the sealing portion of the molded portion. xe2x80x9cTPExe2x80x9d embraces an olefin-based TPE (TPO) and styrene-based TPE (SBC). Especially, a soft TPO is preferably used from the standpoint of adhesion with the attachment portion of the extruded portion or the molded portion. As a molding material for the attachment portion of the molded portion, an olefin-based resin such as polyethylene or polypropylene having a Shore D type hardness of 30xc2x0 to 65xc2x0 may be used for example. Especially, a polyethylene resin is preferably used from the standpoint of adhesion relative to EPDM as an olefin-based rubber.
As the resin for the decorative cover, a polyolefin resin such as polyethylene or polypropylene can be used for example. On the other hand, TPO and SBC or the like can be exemplified as the TPE for the decorative cover. Moreover, a foamed material of the resin or TPE can also be used. It is preferred that a pattern such as an embossed pattern is illustrated on the surface of the decorative cover. Of course, when the pattern is formed, a design of an identical pattern is also provided on the outer surface for the attachment portion and/or the covering lip portion of the molded portion.
Further objects of this invention will become evident upon an understanding of the illustrative embodiments described below. Various advantages not specifically referred to herein but within the scope of the instant invention will occur to one skilled in the art upon practice of the presently disclosed invention. The following examples and embodiments are illustrated and not seen to limit the scope of the invention.